This is another one I'm on the fence about. I get that caffeine can increase your heart rate therefore causing more movement when you shoot. But I mean, I really need a nice mocha in the morning to wake me up. If I don't have a coffee in the morning then I may be more likely to make a technical mistake, like not loading a pellet or measuring distance wrong. And by the time you get there, sight-in and actually start shooting just how much is left in you? Not sure.
There are some people that quit caffeine all-together at least two days before a match and others that just don't have caffeine before they shoot.
I guess it all depends on how serious you are and how caffeine affects you. Every shot I take in the basement has caffeine through and through. Maybe it's a matter of making sure you have something to eat and then have your coffee, so it isn't racing through your system all at once?
I'm sure this is an individual thing, but because it is individual that means that you have to be very aware of your body and how it reacts to these types of things.